Rhinomcp.rhp initialization failed - Rhino 8 SR29 Windows 11

Rhino AI
1

Hi everyone,

I’m trying to connect Claude AI to Rhino 8 using RhinoMCP but the plugin won’t load.

My setup: - Rhino 8 SR29 (8.29.26063.11001) - Windows 11 (10.0.26200.0) - .NET SDK 8.0.419 installed - Visual C++ 2015-2022 Redistributable already installed - Python 3.9.13 installed - uv/uvx installed and working

What I tried: - Installing via Package Manager (rhinomcp v0.2.1) - Installing via yak.exe from PowerShell - Dragging rhinomcp.rhp directly into Rhino - Running Rhino as Administrator - Uninstalling and reinstalling multiple times

The error I always get: “Unable to load rhinomcp.rhp plug-in: initialization failed” The Details button shows no useful information.

The uvx rhinomcp server works fine in PowerShell, so the Python side is working correctly.

Any help would be greatly appreciated!

4

Same issue here, confirming this is still happening on the latest stable release, not just a beta build.

Setup: Rhino 8 SR34, Windows. Tested with “Rhino MCP Platform” via Yak Package Manager:

  • Beta 0.2.1-wip — fails
    • Latest stable 0.1.5 — fails identically
  • Exact error: “Unable to load the RhinoMcpPlatform.rhp plug-in: initialization failed.” The Details button shows no useful info, same as reported above.

I also checked Task Manager for lingering rhino-mcp-router.exe processes in case of a port conflict — none found, so that’s ruled out on my end too.

Would love to know if there’s a known fix, or if this needs a proper bug report to the dev team. Trying to use this for a Grasshopper + Claude workflow for chocolate mold design. Happy to share more logs if it helps.

5

Can you post your SystemInfo?

I suspect you’re running net48